outlook 2007 error 550 relaying prohibited

[rickster]

We have an employee who vpns into our network and runs outlook 03 on xp to
send and receive mail from our exchange 5.5 server, everything works fine.
The employee then upgraded to outlook 2007 and vista, now he can send mail
internally in our company but receives ndr '550 relaying prohibited' when he
tries to send internet mail, even though he's still connected thru our vpn.
Any clues to why he's getting internet mail returned?

 

[Brian Tillman]

We have an employee who vpns into our network and runs outlook 03 on
xp to send and receive mail from our exchange 5.5 server, everything
works fine. The employee then upgraded to outlook 2007 and vista, now
he can send mail internally in our company but receives ndr '550
relaying prohibited' when he tries to send internet mail, even though
he's still connected thru our vpn. Any clues to why he's getting
internet mail returned?

He's not properly authenticating to the outgoing server.